with these 3 examples, each work by themselves (cvalue & mvalue) but when I do both I get:invalid assignment left-hand side

Here is what the streamed js looks like for each:#both (broken)onblur=\\\"new Ajax.Updater(\'dd_urltobuy\',\'/tasks/manu_changed?id=1&amp;mvalue=\'+$F(\'task_tmodel\')&amp;cvalue=\'+this.value, {asynchronous:true, evalScripts:true});